The problem is that ado driver creates a link file in the tree
leaving it dirty: tinderbox doesn't like it. Instead of reading
the mdb file direct from srcdir we copy it first to workdir and
read it from there with the new function: getPathFromWorkdir.
Thank you Norbert!

Change-Id: I504bc26b80686db55a505bac19a95cc9c6022fcc
Reviewed-on: https://gerrit.libreoffice.org/1004Reviewed-by: Norbert Thiebaud <nthiebaud@gmail.com>
Tested-by: Norbert Thiebaud <nthiebaud@gmail.com>